Process and apparatus for releasing obstructions in discharge openings of concentrating pans



Jan. 17, 1956 E. HARVENGT 2,731,143 1 PROCESS AND APPARATUS FOR RELEASING OBSTRUCTIONS IN DISCHARGE OPENINGS 0F CONCENTRATING PANS Filed June 28, 1951 3 Sheets-Sheet l 00 2 4- t 1 M 7 11 3 k y a 28 e N h 0 s I T 3 C U R T 5 Jan. 17, 1956 E. HARVENGT PROCESS AND APPARATUS FOR RELEASING OB IN DISCHARGE OPENINGS OF CONCENTRATING PANS Filed June 28, 1951 Jan. 17, 1956 E. HARVENGT 2,731,148

PROCESS AND APPARATUS FOR RELEASING OBSTRUCTIONS INDISCHARGE OPENINGS OF CONCENTRATING PANS Filed June 28, 1951 5 Sheets-Sheet 5 United States Patent PROCESS AND APPARATUS FOR RELEASING OBSTRUCTIONS 1N DISCHARGE OPENINGS OF CONCENTRATING PANS Edmond Harvengt, Moustier sur Sambre, Belgium, assignor to Link-Belt Company, Chicago, 11]., a corporation of Illinois Application June 28, 1951, Serial No. 234,097

18 Claims. (Cl. 209--465) The invention has relation to pans. It is known that Such apparatus, which are mainly used to ensure the separation of ores-the term ores being used in its broader sense-of comparatively high density from their comparatively light gangues or slags, are often required to operate under unfavorable conditions as regards the homogeneity of the treated materials, in that the latter are often accompanied by waste products of all kinds causing obstructions in the discharge openings, and especially the discharge openings for the dense products. Aside from the necessity for an almost permanent supervision, the resulting stops in the operation are not only detrimental to the quantitative yield, but also unfavorably affect the separation taking place in these apparatus.

The main object of the invention is to remedy this drawback. According to the invention, in order that the obstructions occurring at the discharge openings of pans may be avoided at least to a large extent, there is normally caused to pass through these openings at liquid current of moderate intensity, flowing in a direction opposite that of the discharged material, and the intensity of the said current is increased in correlation with the degree of obstruction of said openings until the release thereof is obtained. The current of increased intensity may be steady or pulsatory.

According to another feature of the invention, the change in intensity of the normal current is controlled by the change, due to the obstruction, either in the flow of the current through the discharge openings or in the quantitles of materials discharged through said openings.

According to one convenient manner of carrying out the method in accordance with the invention, the evacuation of the materials discharged through the openings of the pans is arranged so that it may be effected with no, or only a small quantity of, accompanying liquid from a chamber adjoining each opening and in free communication therewith. With eachchamber there is connected a liquid supply that creates the current. The opening and closing of said liquid supply is controlled by suitable means, which, preferably may be either hydraulically, pneumatically or mechanically actuated.

Due to the liquid current, in accordance with the invention, there is obtained not only an easy release of the discharge openings of the pans but, also, owing to the permanent flow of this current of moderate intensity through these openings, the quality of the. discharged material is improved.

in order that the invention may be well understood, it will now be described in greater detail in connection with the preferred arrangements .of apparatus, given by way of examples only, and illustrated in the accompanying drawings in which:

Figure 1 is a vertical sectional view of a pan, the dischargeof materials from which isobtained in accordance with the invention;

-' Figures 2 and 3 are similar views to Fig. l but of other embodiments;

Figures 4 and 4 a illustrate in vertical sect-ion another 2,731,148 Patented Jan. 17, less embodiment with the parts being shown in two diiferent positions of operation, and

Figures 5, 6 and 7 are similar views to Fig. 1 and show further embodiments of the invention.

Referring to the drawings and first to Fig. 1, 1 designates the basin of a pan provided in the usual manner with stirring arms 2 arranged on a central and vertical rotating shaft 3, and with an inlet 4 for the materials to be treated. Upon completion of their treatment in the pan, these materials are discharged, the light products through a central opening 5 and the dense products through an opening 6 located at the periphery and formed in the lower portion of the basin, preferably in the bottom wall thereof.

Owing to waste products of all kinds accompanying in most cases the treated materials, an opening such as 6 often shows av tendency to become obstructed.

To remedy this, in accordance with the invention, there is normally caused to pass through the opening 6 a liquid current of moderate intensity, and the intensity of which is increased in case of obstruction. To this end, in the illustrated arrangement, there is associated with this opening a chamber 7 the bottom of which is provided with a discharge device for the dense products which is adapted to avoid any considerable discharge of accompanying liquid, and into which chamber a moderate quantity of liquid is normally introduced.

In the example ,of Fig. 1,. the discharge device comprises the assembly of two rollers 8 and 9 made of resilient material, or provided with a covering made of resilient material, and rotating continuously in opposite directions. For this purpose, one at least of the rollers is actuated for example by means of a belt 10 driven from the rotating shaft 3, or in any other convenient manner.

As will be understood in such a device, the granular material 11, occupying the chamber 7 or falling through the opening 6, will have its grains taken between and carried by the rotating rollers 8 and 9, said grains causing in the material of the rollers, or in the coverings thereof, cells to be formed the walls of which closely accommodatethe outlines of the grains without the substantial carrying of liquid therewith, not withstanding the fact that the chamber 7 is full of liquid.

The liquid inlet illustrated by the pipe 12 is provided with an obturating device such as a cock 13 and is connected to any suitable supply of liquid under pressure, not illustrated.

The chamber 7 is provided with an upwardly directed extension 14 closed in the upper part thereof by means of a flexible diaphragm 15. Where necessary, such a diaphragm may be loaded by a weight 16 in'order to be normally curved in a downward direction. The upstanding rod 17 is connected by means of a lever 18,

pivoted at 19 to a fixed bracket 20, to a rod 21 employed for actuating the operating lever 22 of the obturating device 13.

The arrangement is such that in the positions of the parts as shown in the figure, the obturating device 13 occupies an open position for delivering a moderate quantity of liquid to the chamber 7. This liquid passes from the chamber '7 upwardly through the opening 6 to enter the basin of the pan. The liquid also enters the extension 14 and traps an air cushion between the liquid and the diaphragm. Due to the liquid passing through the opening 6, the compression of the air cushion, and the force with which the diaphragm 15 opposes deformation, a balance is reached which controls the intensity of the liquid current passing through the said opening.

When an obstruction occurs at the opening 6, due, for example, to jamming in, or an accumulation above, the opening, which may be caused by waste foreign products, with or without grains of the materials to be evacuatcd, the resistance to the flow of the liquid current through the opening increases in proportion. The result is that the liquid being delivered to the chamber, and which is no longer able to pass through the opening 6, accumulates within the extension 14 where it compresses the air cushion which, in turn, increases the pres sure on and further distorts the diaphragm 15 in an upward direction.

Therefore, the elements 17, 18, 21 and 22 will move the obturating device 13 further towards its fully open position with the result that a greater flow of liquid into the chamber 7 will occur. Thus the liquid acts with an increased pressure on the materials obstructing the opening and on the diaphragm and this action will be continued and amplified by the further opening of the obturating device 13 until the pressure has become sufficient to overcome the obstruction.

The released opening 6 then allows for the passage of the excess liquid from the chamber 7. The parts then will resume the positions of Fig. 1 and will restore the moderate flow of the liquid current through the opening 6 until this opening is again obstructed and the described operations are repeated.

It will be observed that the ascending flow of the moderate liquid current through the opening 6 will enable a more efiicient separation of the dense products discharged at 6 from the light products evacuated at to be obtained because it provides a means for retaining in, or returning to, the basin of the pan the particles of lesser density than those of which the discharge at 6 is intended. permits the size of the opening 6 to be increased to a certain extent, thus minimizing the danger of the opening 6 becoming obstructed.

Instead of a diaphragm such as 15, a piston-cylinder assembly 14a-15a could be provided, and such an arrangement is illustrated in Fig. 2 the operation being in other respects the same as in Fig. 1.

In accordance with Fig. 3, wherein the same parts are designated by similar reference numerals, the chamber 7 could again be closed at the bottom by means of a pair of rollers of resilient material, or provided with a resilient covering, as in Fig. 1.

However, the discharge device is illustrated as being formed with a drum 23 having pockets 24 for receiving the material to be discharged. This material is discharged at 25, with a small quantity of liquid only, in an intermittent manner by means of the mechanism now to be described, or a similar mechanism.

This mechanism comprises a partition 26 arranged at an intermediate level of the chamber 7 and extending the entire length thereof. This partition is suitably curved in cross-section and it cooperates with a shutter 27, also extending the entire length of the chamber 7, which is oscillated by means of a lever 28 made integral with its pivoting trunnion 29 journaled in the end walls of the chamber 7. The lever 28 may be oscillated in any suitable manner and is conveniently actuated by means of the connecting rod 30 of an eccentric 31 conveniently mounted on the shaft of the pocketed drum 23. The arrangement is such that in the movements effected by the shutter 27 with its free edge rubbing, or almost rubbing, on the partition 26, said shutter forms periodically between its edge and the partition 26, an opening for the materials which, during the interval, have passed through. the opening 6 and are loading the partition 26. In this way, these materials fall in the pockets 24 of the drum 23 and are carried thereby outside the chamber 7.

To release the opening 6 should obstructions occur similarly to Figs. 1 and 2, a liquid inlet 12, controlled by means of an obturating device 13, is arranged to open into the chamber 7. The operation of the obturating device is ensured, for example, by means of a deformable diaphragm 15 made of a material having resilient properties. This diaphragm is mounted in a wall of the chamber 7 and is connected to the operating lever 22 of the It also v obturating device by means of a rod 17 slidable in a mount 17a secured to the basin 1. The rod 17 is provided with an abutment 17b against which bears a return spring 170 the force of which may be adjusted by changing the position of the abutment 17b on the rod 17. The arrangement is such that when an obstruction occurs at the opening 6, the liquid introduced into the chamber 7 through the inlet 12 will increase the pressure in the said chamber and this increase in pressure will cause the diaphragm to flex. This actuation of the diaphragm, acting through the drive 1722 will bring about a further opening of the obturator 13 and an increase in the intensity of the liquid entering the chamber 7 and tending to pass through the opening 6. Should the obstruction resist this increased fluid pressure, the distortion of the diaphragm will be increased and the obturator 13 will be further opened, this process being continued until the pressure of the liquid becomes suflicient to overcome the obstruction.

When this occurs, the resulting fall in pressure within the chamber 7 enables the diaphragm to resume its initial position with the aid of the spring 170, restoring also to its initial value the intensity of the liquid supplied by the pipe 12.

In the embodiments of Figs. 4 and 4a, the arrangement of the chamber 7 is similar to that of Fig. 3, but the operating drive for ensuring the opening and closing of the obturator 13 is arranged as follows, or in a similar manner.

On the partition 26 is arranged an oscillatable panel 32, pivoted at 33 and balanced by means of an adjustable counterweight 33a, in such a way that when the materials pass in sufficient quantity through the opening 6 and load the panel 32, the latter occupies a position closely adjacent the partition and does not in any way interfere with the oscillatory movement of the shutter 27. To the contrary, should the passage of the materials through the opening 6 be prevented or considerably reduced, due to the action of the counterweight 32a, the panel 32 will be raised sufficiently to enter the path of the shutter 27 and prevent, or considerably reduce, the upward oscillation thereof. On the other hand, the connecting rod of the eccentric 31 is extended past its connection 34 with the lever 28 of the oscillating shutter 27 by slidably passing through this connection. On the extension of the connecting rod 30 is mounted a spring 36 that is held under compression by means of an abutment 35. The force of the spring is such that when the panel 32 is not appreciably spaced from the partition 26, the shutter 27 is positively actuated in a normal manner by the eccentric 31. However, when the panel 32 is raised, it will stop, or partially restrict, the upward movement of the shutter with the result that the connecting rod 30, operated by the eccentric 31, will slide in the connection 34 against the action of the spring 36.

Observing that all points of the connecting rod 30 follow trajectories which are different when the connection 34 is carried by the lever 28 than when it is held stationary, due to the stopping of the oscillation of the shutter 27, use is made of this peculiarity for controlling the movement of the lever 37 operating the obturator 13 in order to increase the intensity of the liquid current entering the chamber 7 and passing through the opening 6 and subsequently to restore same to its initial value.

Thus, as shown in Figs. 4 and 4a, by giving the operating lever 37 of the obturator 13 a forked shape, the end of one branch enters the trajectory traced, for example, by the abutment when the connecting rod 30 slides in the connection 34, while the end of the other branch enters the trajectory of this abutment-or of any other more convenient point of the connecting rodwhen the said connecting rod positively moves the lever 28. Due to this relationship, the obturator 13 will operate for increasing the intensity of the liquid current when the materials no longer pass, or pass in insufficient quantities,

through the opening 6, see Fig. 4a, while it will operate to reduce said intensity and return to the position corresponding to the flow of a liquid current of moderate intensity, see Fig. 4, 'while the normal conditions of passage of the materials at the opening 6 are restored.

In Fig. 5, the arrangement is similar to that of Fig. 4, except that the partition 26 as a whole has a considerable downward slope, the shutter 27 mainly forming the support for the materials to be evacuated at the opening 6. In this case the movable, balanced panel 32 is conveniently associated with the shutter 27 and, as illustrated, is provided with an arm 38 which may be integral with its oscillating shaft-or of any other part of the panel--and which is arranged to strike the partition 26 when the panel 32, while rising, moves away from. the shutter 27. By suitably arranging an abutment on the partition 26, for example, at the lower end thereof as at 39, there is again obtained a stoppage or a decrease in amplitude of the oscillatory movement of the shutter 27 when the materials no longer pass, or pass in insuflicient quantity, through the opening 6. This stoppage or amplitude decrease of the oscillatory movement is used in a manner similar to that described with reference to Fig. 4 for controlling the intensity of flow of the liquid through the supply conduit 12.

The lower portion of the chamber 7 may be equipped with a pocketed drum as in Figs. 3 and 4, or alternatively as shown, with a discharge device comprising rollers of resilient material or provided with a resilient covering, as in the arrangement of Figs. 1 and 2.

In the construction according to Fig. 6, the arrangement of the chamber 7 is similar to that of Fig. 4, but the opening and closing movements of the obturator 13 are controlled by means of a device such as follows:

Below the discharge opening 25' of the pocketed drum 23 for the discharge of products coming from the opening 6, there is arranged a support 40, preferably perforated, made integral with a pivoting shaft 41 journaled within a fixed mounting 42, and balanced by means of an adjustable counterweight 43 sliding on a lever 44 and connected by a rod 45 to the operating lever 22 of the obturator 13'. This arrangement is such that when the evacuation of the product is normal, that is, when the opening 6 is not obstructed, the support 40 will be loaded with material and will occupy a position-indicated in heavy dotted lines-at which the obturator 13 will allow the passage of a liquid current of moderate intensity into the chamher 7 and through. the opening 6. It will be understood that this position of the support 40 permits the discharged materials to pass at their delivery rate into the associated evacuating channel 46. When the discharge at 25 is stopped, or becomes insufiicientwhich corresponds to an obstruction of the opening 6-the support 40, urged by the counterweight 43, rises and a rod 45 operates on lever 22 to open progressively the obturator 13. This action increases the intensity of the liquid current entering the chamber 7 until the release of the opening 6 is obtained as previously explained. When the opening 6 is freed of the obstruction, the discharge takes place again at 25- With the simultaneous lowering of the support 40 and the return of the obturator 13 to the position allowing for the passage of the normal current of moderate intensity. An abutment 47, which is preferably rendered adjustable, may be provided in the path of the lever 44 for determining the normal position of the obturator 13.

In the embodiments described, while the current of increased intensity is variable it is nevertheless a steady or continuous current. It is within the limits of the invention to have this current made pulsatory. This may facilitate the release of the opening 6 and has the advantage of functioning, when the intensity of the current is too great, to prevent or considerably delay the restoration of. the discharge through this opening after the latter has been freed of the obstruction.

Fig. '7 shows, by way'of example, one method of obtaining a pulsatory liquid current of increased intensity. To this end, the shaft 48 is equipped with a cam 49 that periodically operates on an abutment, for example a roll 50 rotatable on its axis and mounted on the support 40 when said support occupies its raised position. In this way the obturator 13, which has been progressively moved into a position of greater opening by the raising of the support 40, is periodically more or less closed and the liquid current entering the chamber 7 is rendered pulsatory. Upon release of the opening 6, the discharge of the materials may always be resumed during the periods of decreasing intensity of the current, thus ensuring the return of the parts of the device to their initial positions.

In the arrangements according to Figs. 6 and 7, as well as in the arrangements of Figs. 3 and 4, instead of a pocketed drum, use may be made of a pair of rolls of resilient material, or having a resilient covering, and conversely a pocketed drum may be used in arrangements such as illustrated in Figs. 1, 2 and 5.

Similarly, the controlling by mechanical means of the change in the intensity of the liquid current according to Figs. 6 and 7 can be caused by a control elfected with the aid of hydraulic or hydro-pneumatic means, of the kind illustrated in Figs. 1 to 3, such hydraulic or hydro-pneumatic control being used as an additional safety means, or to ensure either the opening or closing operation of the obturator 13.

It is also to be understood that other modifications may be made in the details of the described arrangements, for example, a liquid inlet of moderate intensity, adjusted once and for all, and a normally closed liquid inlet which is opened in case the discharge opening 6 becomes obstructed, could be provided without exceeding the limits of the invention.

I claim:

1. A process for releasing obstructions from the discharge openings of concentrating pans, comprising normally continuously supplying liquid at a moderate intensity to a confining zone adjacent the pan, passing a current of liquid from said zone through said openings in the opposite direction to that of the discharge of the materials, accumulating in said zone the part of said supply liquid that is prevented from passing through the openings when an obstruction occurs therein, and increasing theintensity of the liquid supplied to the confining zone in proportion to any increase that occurs in the pressure of the liquid accumulated in said zone.

2 A device for releasing obstructions from thedischarge openings of concentrating pans, comprising a pan basin having a material discharge opening, a chamber attached to the basin to receive the material discharged through said opening, a material and liquid discharge opening for said chamber, means operatively associated with the chamber discharge opening for effecting the discharge of material, and for materially restricting the rate of discharge of liquid, through said opening, a liquid supply line communicating with the chamber, adjustable valve means in said supply line normally set to deliver liquid to the chamber at a sufliciently greater rate than the restricted rate of discharge of liquid from the chamber to maintain the chamber filled with liquid to the level of the material discharge opening of the pan basin and at a fluid pressure, when the pan basin opening is unobstructed, to produce a normal flow of liquid through the opening at a moderate intensity and in the opposite direction to the discharge of material from the pan basin, means operable in response to variations in the amount of material entering the chamber through the discharge opening of the pan basin, and means connecting the said operable means to the adjustable valve means in the liquid supply line for adjusting the said valve means in relation to any reduction in the rate of discharge ofniateri'al through the said pan basin discharge opening, due to the obstructing of said latter opening, to increase the rate of flow of liquid into' the chamber and thereby the intensity of the said flow of liquid from the chamber through the material discharge opening of the pan basin to effect release of the obstruction 3. The device of claim 2 further characterized by the means operable in response to variations in the amount of material entering the chamber through the discharge opening of the pan basin, comprising a partition extending partially across the chamber, a shutter oscillatably mounted in the chamber and cooperating with the partition for alternately opening and closing a passageway through the chamber for the material discharged through the pan basin opening, means for imparting an oscillatory movement of substantially constant amplitude to the shutter, means responsive to the amount of material discharged through the pan basin opening for reducing the amplitude of the oscillatory movements of the shutter when an obstruction occurs in said pan basin discharge opening, and means connecting the shutter and the adjustable valve means for adjusting the latter means in relation to the changes in the amplitude of the oscillatory movements of the shutter.

4. The device of claim 3 further characterized by the means for reducing the amplitude of oscillatory movements of the shutter including a balanced panel mounted on and movable relative to the shutter as a result of a substantial reduction in the amount of material discharged through the pan basin opening, and abutment means cooperating with said panel when so moved relative to the shutter.

5. The device of claim 3 further characterized by the means for reducing the amplitude of oscillatory movements of the shutter including a balanced panel mounted on and movable away from the partition into the path of movements of the shuter as a result of a substantial reduction in the amount of material discharged through the pan basin opening.

6. The device of claim 3 further characterized by the means operatively associated with the chamber discharge opening including a rotatable discharge means, and the means for imparting an oscillatory movement to the shutter comprising an eccentric device operated by said rotatable discharge means and including a connecting rod, a lever for oscillating the shutter, a slidable connection between said connecting rod and the lever for operating the latter, a double-armed lever operatively connected to the adjustable valve means in the liquid supply line, and means for causing each branch of said double-armed lever to cooperate with a trajectory portion of an end of said connecting rod when the latter positively operates the oscillatable lever and slides in said slidable connection, respectively.

7. A device for releasing obstructions from the discharge openings of concentrating pans, comprising a pan basin having a material discharge opening, a chamber attached to the pan basin to receive the material discharged through said opening, a material and liquid discharge opening for said chamber, means operatively associated with the chamber discharge opening and including a driven rotatable discharge member for effecting the discharge of material, and for materially restricting the rate of discharge of liquid, through said opening, a liquid supply line communicating with the chamber, adjustable valve means in said supply line normally set to deliver liquid to the chamber at a suificiently greater rate than the restricted rate of discharge of liquid from the chamber to maintain the chamber filled with liquid to the level of the material discharge opening of the pan basin and at a fluid pressure, when the pan basin opening is unobstructed, to produce a normal flow of liquid through the opening at a moderate intensity and in the opposite direction to the discharge of material from the pan basin, an oscillatable support located below said rotatable discharge member for receiving the material discharged by the said member, an adjustable balancing device for the oscillatable support, and means connecting said oscillat- 8 able support and the adjustable valve means for adjusting the latter means in relation to the amount of material occupying said oscillatable support.

8. The device of claim 7 further characterized by a cam driven by the rotatable discharge member, and an operating roll mounted on the oscillatable support and engageable by said cam when said oscillatable support is occupied by a relatively small amount of material for imparting periodic oscillatory movements to the oscillatable support to thereby impart periodic adjustments to the said adjustable valve means.

9. A device for releasing obstructions from the discharge openings of concentrating pans, comprising a pan basin having a material discharge opening, a chamber attached to the pan basin to receive the material discharged through said opening, a material and liquid discharge opening for said chamber, means operatively associated with the chamber discharge opening for effecting the discharge of material, and for materially restricting the rate of discharge of liquid, through said opening, a liquid supply line communicating with the chamber, adiustable valve means in said supply line normally set to deliver liquid to the chamber at a sufficiently greater rate than the restricted rate of discharge of liquid from the chamber to maintain the chamber filled with liquid to the level of the material discharge opening of the pan basin and at a fluid pressure, when the pan basin opening is unobstructed, to produce a normal flow of liquid through said opening at a moderate intensity and in the opposite direction to the discharge of material from the pan basin, and automatically operative means for adjusting the valve means in relation to any reduction in the rate of discharge of material through the said pan basin opening, due to the obstructing of said latter opening, to increase the rate of flow of liquid into the chamber and thereby the intensity of the said flow of liquid from the chamber through the material discharge opening of the pan basin to effect release of the obstruction.

10. A device for releasing obstructions from the discharge openings of concentrating pans, comprising a pan basin having a material discharge opening, a chamber attached to the pan basin to receive the material discharged through said opening, a material and liquid discharge opening for said chamber, means operatively associated with the chamber discharge opening for elfecting the discharge of material, and for materially restricting the rate of discharge of liquid, through said opening, a liquid supply line communicating with the chamber, adjustable valve means in said supply line normally set to deliver liquid to the chamber at a sufiiciently greater rate than the restricted rate of discharge of liquid from the chamber to maintain the chamber filled with liquid to the level of the material discharge opening of the pan basin and at a fluid pressure, when the pan basin opening is unobstructed, to produce a normal flow of liquid through said opening at a moderate intensity and in the opposite direction to the discharge of material from the pan basin, one 05 the walls of said chamber having an opening therein, a yieldable closure for said Wall opening movable in response to an increase in the fluid pressure in said chamber resulting from any obstructing of the pan basin opening, and means operatively connecting the yieldable closure to the valve means to cause movement of the closure to effect a corresponding adjustment of the valve means to increase the rate of flow of liquid into the chamber and thereby the intensity of the said flow of liquid from the chamber through the material discharge opening of the pan basin to effect release of the obstruction.

11. The device defined in claim 10 further characterized by the yieldable closure comprising a diaphragm of resilient material.

12. The device defined in claim 10 further characterized by the yieldable closure comprising a diaphragm and means for loading the diaphragm against the fluid pressure in the chamber.

13. A device for releasing obstructions from the discharge openings of concentrating pans, comprising a pan basin having a material discharge opening, a chamber attached to the pan basin to receive the material discharged through said opening, a material and liquid discharge opening for said chamber, means operatively associated with the chamber discharge opening for eflecting the discharge of material, and for materially restricting the rate of discharge of liquid, through said opening, a 'liquid supply line communicating with the chamber, adjustable valve means in' said supply line normally set to deliver liquid to the chamber at a sufficiently greater rate than the restricted rate of discharge of liquid from the chamber to maintain the chamber filled with liquid to the level of the material discharge opening of the pan basin andat a fluid pressure, when the pan basin opening is unobstructed, to produce a normal flow of liquid through said opening at a moderate intensity and in the opposite direction to the discharge of material from the pan basin, an extension for the chamber located above the level of the material discharge opening of the pan basin, said extension having an opening in one wall thereof a yieldable closure for said extension opening movable in response to an increase in the fluid pressure in said chamber resulting from any obstructing of the pan basin opening, and means operatively connecting the yieldable closure to the valve means to cause movement ofthe' closure to effect a corresponding adjustment of the valve means to increase the rate of flow of liquid into the chamber and thereby the intensity of the said flow of liquid into the chamber through the material discharge opening of the pan basin to effect release of the obstruction.

14. A device for releasing obstructions from the discharge openings of concentrating pans, comprising a pan basin having a material discharge opening, a chamber attached to the pan basin to receive the material discharged through said opening, a material and liquid discharge opening for said chamber, means operatively associated with the chamber discharge opening for effecting the discharge of material, and for materially restricting the rate of discharge of liquid, through said opening, a liquid supply line communicating with the chamber, adjustable valve means in said supply line normally set to deliver liquid to the chamber at a sufliciently greater rate than the restricted rate of discharge of liquid from the chamber to maintain the chamber filled with liquid to the level of the material discharge opening of the pan basin and at a fluid pressure, when the pan basin opening is unobstructed, to produce a normal flow of liquid through said opening at a moderate intensity and in the opposite direction to the discharge of material from the pan basin, and automatically operative means for adjusting the valve means in relation to any increase that occurs in the pressure of the fluid in the chamber due to the obstructing of the said pan basin opening to increase the rate of flow of liquid into the chamber and thereby the intensity of the said flow of liquid from the chamber through the material discharge opening of the pan basin to efiect release of the obstruction.

15. A device for releasing obstructions from the discharge openings of concentrating pans, comprising a pan basin having a material discharge opening, a chamber attached to the pan basin to receive the material discharged through said opening, a material and liquid discharge opening for said chamber, means operatively associated with the chamber discharge opening for effecting the discharge of material, and for materially restricting the rate of discharge of liquid, through said opening, a liquid supply line communicating with the chamber, adjustable valve means in said supply line normally set to deliver liquid to the chamber at a sufliciently greater rate than the restricted rate of discharge of liquid from the chamber to maintain the chamber filled with liquid to the level of the material discharge opening of the pan. basin and at a fluid pressure, when the pan basin opening, is unobstructed, to produce a normal flow of liquid through said opening at a moderate intensity and in the opposite direction to the discharge of materialfrom the pan basin, one of the walls of said chamber having an opening therein, a yieldable closure for said wall opening movable in response to an increase in the fluid pressure in said chamber resulting from any obstructing of the pan basin opening, spring means for loading said yieldable wall closure in an inward direction relative to said chamber, and means operatively connecting the yieldable closure to the valve means to cause movement of the closure to effect a corresponding adjustment of the valve means to increase the rate of flow of liquid into the chamber and thereby the intensity of the said flow of liquid from the chamber through the material discharge opening of the pan basin to effect release of the obstruction.

16. A device for releasing obstructions from the discharge openings of concentrating pans, comprising a pan basin having a material discharge opening, a chamber attached to the pan basin to receive the material discharged through said opening, a material and liquid discharge opening for said chamber, rotatably driven means operatively associated with the chamber discharge opening for eflecting the discharge of material, and for materially restricting the rate of discharge of liquid, through said openings, an oscillating shutter positioned in the chamber to control the rate of feed of material through the chamber to the rotatably driven discharge means, a drive connection between the shutter and the discharge means to oscillate the shutter in timed relation to the rotary movement of the discharge means, a liquid supply line communicating with the portion of the chamber located above the said shutter, adjustable valve means in said supply line normally set to deliver liquid to the chamber at a sufiiciently greater rate than the restricted rate of discharge of liquid from the chamber to maintain the chamber filled with liquid to the level of the material discharge opening of the pan basin and at a fluid pressure, when the pan basin opening is unobstructed, to produce a normal flow of liquid through said opening at a moderate intensity and in the opposite direction to the discharge of material from the pan basin, and automatically operative means for adjusting the valve means in relation to any reduction in the rate of discharge of material through the said pan basin opening, due to the obstructing of said latter opening, to increase the rate of flow of liquid into the chamber and thereby the intensity of the said flow of liquid from the chamber through the material discharge opening of the pan basin to effect release of the obstruction.

17. A device for releasing obstructions from the discharge openings of concentrating pans, comprising a pan basin having a material discharge opening, a chamber attached to the pan basin to receive the material discharged through said opening, a material and liquid discharge opening for said chamber, rotatably driven means operatively associated with the chamber discharge opening for effecting the discharge of material, and for materially restricting the rate of discharge of liquid, through said opening, an oscillating shutter positioned in the chamber to control the rate of feed of material through the chamber to the rotatably driven discharge means, a drive connection between the shutter and the discharge means to oscillate the shutter in timed relation to the rotary movement of the discharge means, a liquid supply line communicating with the portion of the chamber located above the said shutter, adjustable valve means in said supply line normally set to deliver liquid to the chamber at a sufliciently greater rate than the restricted rate of discharge of liquid from the chamber to maintain the chamber filled with liquid to the level of the material discharge opening of the pan basin and at a fluid pressure, when the pan basin opening is unobstructed, to produce a normal fiow of liquid through said opening at a moderate intensity and in the opposite direction to the discharge of material from the pan basin, one of the walls of said chamber having an opening therein, a yieldable closure for said wall opening movable in response to an increase in the fluid pressure in said chamber resulting from any obstructing of the pan basin opening, and means operatively connecting the yieldable closure to the valve means to cause movement of the clo sure to effect a corresponding adjustment of the valve means to increase the rate of flow of liquid into the chamber and thereby the intensity of the said flow of liquid from the chamber through the material discharge opening of the pan basin to eilect release of the obstruction.

18. A device for releasing obstructions from the discharge openings of concentrating pans, comprising a pan basin having a material discharge opening, a chamber attached to the pan basin to receive the material discharged through said opening, a material and liquid discharge opening for said chamber, rotatably driven means operatively associated with the chamber discharge opening for efiecting the discharge of material, and for materially restricting the rate of discharge of liquid, through said opening, an oscillating shutter positioned in the chamber to control the rate of feed of material through the chamber to the rotatably driven discharge means, a drive connection between the shutter and the discharge means to oscillate the shutter in timed relation to the rotary movement of the discharge means, a liquid supply line communicating with the portion of the chamber located above the said shutter, adjustable valve means in said supply line normally set to deliver liquid to the chamber at a sufficiently greater rate than the restricted rate of discharge of liquid from the chamber to maintain the chamber filled with liquid to the level of the material discharge opening of the pan basin and at a fluid pressure, when the pan basin opening is unobstructed, to produce a normal flow of liquid through said opening at a moderate intensity and in the opposite direction to the discharge of material from the pan basin, one of the walls of said chamber having an opening therein, a yieldable closure for said Wall opening movable in response to an increase in the fluid pressure in said chamber resulting from any obstructing of the pan basin opening, spring means for loading said yieldable wall closure in an inward direction relative to said chamber, and means operatively connecting the yieldable closure to the valve means to cause movement of the closure to effect a corresponding adjustment of the valve means to increase the rate of flow of liquid into the chamber and thereby the intensity of the said flow of liquid from the chamber through the material discharge opening of the pan basin to effect release of the obstruction.

References Cited in the file of this patent UNITED STATES PATENTS 501,959 Rawlings July 25, 1893 795,823 Darling Aug. 1, 1905 1,065,288 Whitton June 17, 1913 1,126,818 Michaelsen Feb. 2, 1915 1,162,112 Standefer Nov. 30, 1915 1,247,702 Michael-sen Nov. 27, 1917 1,785,679 France Dec. 16, 1930 2,276,631 Smith Mar. 17, 1942 2,316,783 Geary Apr. 20, 1943 FOREIGN PATENTS 31,539 Norway Dec. 27, 1920 

